c.1600, empirical, from Latin empiricus (n.) "a physician guided by experience," from Greek empeirikos "experienced," from empeiria "experience; mere experience or practice without knowledge," especially in medicine, from empeiros "experienced (in a thing), proven by use," from assimilated form of en "in" (see en-(2)) + peira "trial, experiment," from PIE *per- (3) "to try, risk" (see fear, n.). Originally a school of ancient physicians who based their practice on experience rather than theory. Earlier as a noun (1540s) in reference to the sect, and earliest (1520s) in a sense "quack doctor" which was in frequent use 16c.-19c.